LAKE FOREST, Ill. -- Chicago Bears defensive coordinator Mel Tucker faced a bevy of difficult questions Monday after his group gave up 514 yards against the Philadelphia Eagles in a 54-11 thumping, but displayed confidence when asked if he worried about job security.

“No, I don’t,” Tucker said. “I just stay focused on the task at hand and working to teach, motivate and develop, and work with these guys and get them ready for the next outing. That’s really my main focus.”

In addition to giving up 21 points in both the first and fourth quarters, the Bears allowed LeSean McCoy to run for 133 of Philadelphia’s 291 rushing yards. Chicago allowed two 100-yard rushers in that outing, and on the season they’ve surrendered at least one 100-yard rusher in 10 games.

Chicago's defense, led by coordinator Mel Tucker, hasn't held an opponent to under 20 points this season. AP Photo/Scott Boehm

In the latest setback, Philadelphia reeled off 10 plays for gains of 16 yards or more, with three coming on Nick Foles completions. The Eagles also converted 56 percent of their third-down attempts, and scored touchdowns on five trips into the red zone.

The seven touchdowns scored by the Eagles were the most the Bears have allowed in franchise history (although one of the TDs was on an interception return). The 54 points rank as the second most allowed by the Bears in franchise history.

Earlier in the season, however, Bears head coach Marc Trestman expressed confidence in Tucker’s ability to lead a defense that has been ravaged by a plethora of injuries. Trestman was asked again on Monday about that assessment.

“At the end of the day, and I said this throughout the last two weeks, we did see some work moving forward, and the guys took a step backward [at Philadelphia],” Trestman said. “The only way I can evaluate it is presently. Two weeks of getting a little better at what we were doing, not where we want to be, and a week where we took a step back.”

Is Tucker to blame? Absolutely not. Tucker isn’t missing tackles, busting assignments, not leveraging blocks correctly or just flat out being handled physically by the opponent. And for those who argue that Tucker should be teaching the Bears how to perform fundamentals such as tackling and getting off blocks, you have to realize these guys are NFL players, which means they’ve learned and worked exhaustively on these elements of the game their whole lives.

After all, what team drafts a guy into the NFL that doesn’t know how to tackle?

Tucker’s job is to put the players in the best position to succeed through schemes and game planning. He's done that. But once they’re in position, it’s up to them to make the plays. If the Bears did decide to part ways with Tucker, it would be a major mistake. He's a head coach basically in waiting, and several folks around the league would agree with that assessment.

The Bears won’t use excuses. But injuries are a major part of the defense’s decline, as is the fact the club likely overestimated the type of production they’d get in 2013 from some of their aging veterans, while several of the team's younger players didn't build on what they had done in 2012. The defense has definitely fallen off in 2013, but the truth is the unit started showing signs of decline last season.

Chicago hasn’t held an opponent to fewer than 20 points all season, but in 2012 a mostly healthy Bears defense failed to accomplish that feat in seven of the last 10 games, while also allowing four 100-yard rushing performances.

“Sometimes we’re in the right place, but we’re just not winning the one-on-ones or you missed a tackle. That’s a big part of it,” Tucker said. “Like I said the past couple weeks, it’s not so much now knowing where to fit, it’s when you get there, are you able to shed the block? Are you able to finish on the ball, are you able to make the tackle, are you able to get there quickly enough? That’s part of it, too. We have to eliminate the hesitation, and continue to coach through and work through that as players. That’s pretty much what it is.”